Increased perfusion of the femoral head in transient bone marrow edema syndrome

Presence of subchondral fracture in cases diagnosed as transient osteoporosis of the hip: a retrospective independent reader-based study

OBJECTIVE

Transient osteoporosis of the hip (TOH) is an uncommon, typically self-limited diagnosis of uncertain etiology. We hypothesize that TOH represents an underlying subchondral fracture, and a discrete fracture line can often be detected on high-resolution MRI.

MATERIALS AND METHODS

A retrospective PACS query identified patients meeting imaging criteria for TOH with intense bone marrow edema (BME) in the femoral head on MRI. Those with poor quality studies, other underlying pathologies, or antecedent trauma were excluded. Three musculoskeletal radiologists independently reviewed each case for presence of a definite subchondral fracture line on small field of view (FOV) MR images of the affected hip. Extent of BME, reciprocal acetabular BME, and joint effusion size were also recorded. Binomial logistic regression was performed to determine statistically significant predictors of subchondral fracture.

RESULTS

Fifty patients met inclusion criteria (29 females, 0 pregnant). Mean age was 62±12 years (range 35-84). Average duration of symptoms before MRI was 102±135 days. Ten patients had bone densitometry within 2 years of MRI, six demonstrating osteopenia or osteoporosis. Subchondral fractures were unanimously identified in 44/50 (88%). Interclass correlation coefficient with absolute agreement was 0.73, 95% CI (0.57-0.84), indicating near-excellent agreement. Most cases demonstrated a large joint effusion (23/50, 46%) and acetabular BME (31/50, 62%). Increasing size of joint effusion was a statistically significant predictor of subchondral fracture (p=0.05), with 6.9 higher odds. There was a strong correlation with osteopenia/osteoporosis and fracture (p<0.001).

CONCLUSION

Discrete subchondral fractures were identified unanimously on small FOV imaging in the majority of TOH cases.

ARCO Consensus on the Pathogenesis of Non-traumatic Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is a devastating disease frequently leading to femoral head collapse and hip arthritis. Specifically, non-traumatic ONFH primarily affects young and middle-aged adults. Although compromised local circulation of the femoral head seems to be pathognomonic for the disease, the pathogenesis is perplexing and continues to be an area of scrutiny and research. Comprehension of the pathogenesis is of crucial importance for developing and guiding treatments for the disease. Therefore, we provide an up-to-date consensus on the pathogenesis of non-traumatic ONFH.

Digital Subtraction Angiography and Magnetic Resonance Imaging-Based Staging of Circulatory Obstruction in the Femoral Head During Osteonecrosis of the Femoral Head Development

INTRODUCTION

Nontraumatic osteonecrosis of the femoral head (NONFH) is a common and difficult disease in orthopedics. Magnetic resonance imaging (MRI) assessment of NONFH and bone marrow edema was combined with digital subtraction angiography (DSA) to evaluate the circulatory status of NONFH in different Association Research Circulation Osseous stages. Based on the circulatory obstruction status (venous stasis, arterial ischemia, and arterial occlusion), appropriate perioperative management was adopted to achieve hip joint preservation and effectively delay the time for total hip arthroplasty in young patients.

METHODS

From January 2013 to March 2019, 41 orthopedic patients were evaluated for medical imaging. Sixty-one ONFH cases were enrolled. The inclusion criteria include: (1) Clear diagnosis of osteonecrosis of the femoral head. (2) No history of infection in the affected hip, no history of hip surgery, and no congenital hip diseases. The patients enrolled in this study were 8 women and 33 men between the ages of 19 and 64 years (mean, 39.25 ± 8.90 years). Preoperative X-ray, computed tomography, MRI, DSA, and histological data were taken.

RESULTS

The combination of DSA and MRI can efficiently show blood supply changes in the femoral head of NONFH patients at different Association Research Circulation Osseous stages; and also can possibly reveal the causes and development of NONFH. Different stages of circulatory obstruction of the femoral head can be clearly distinguished and used to determine the required perioperative management, thus yielding successful surgical outcomes.

CONCLUSIONS

The existing classification systems do not fully reflect the progression of circulatory obstruction in ONFH. Each stage of NONFH development has its own characteristics circulatory obstruction. Early-stage NONFH displays characteristic venous stasis of the femoral head, whereas advanced stage NONFH is characterized by insufficient arterial blood supply to the femoral head. Corresponding NONFH treatment strategies should be considered based on their specific circulatory status. This work also provides guidance and recommendations for adopting corresponding femoral head preserving strategies for young patients in different NONFH circulatory status.

High-energy focused extracorporeal shock wave therapy for bone marrow edema syndrome of the hip: A retrospective study

The objective of this retrospective study was to evaluate the efficacy of high-energy focused extracorporeal shock wave therapy (HF-ESWT) on painful bone marrow edema syndrome (BMES) of the hip and shorten the natural course of disease.Thirty-four consecutive patients with BMES of the hip were treated with HF-ESWT in our department between August 2017and July 2018. The progression and treatment results of BMES were evaluated by imaging examination and clinical outcomes. The clinical outcomes include hip pain and function which were measured using the visual analog scale (VAS) and Harris hip score (HHS), respectively, and the VAS and HHS of all patients were calculated and evaluated before treatment (s0), at 1 month (s1), 3 months (s2), 6 months (s3)post-treatment. Imaging examination including Pelvic radiographs and frog views and double hip magnetic resonance imaging (MRI) were also obtained and scheduled before treatment, at 1, 3, 6, and the final follow-up post-treatment to exclude avascular necrosis and other pathology.All patients successfully completed the treatment and follow-up. Compared with pretherapy, the pain was alleviated to varying degrees and the HHS was significantly improved, and the VAS was significantly reduced at S1-2 (1- and 3-months post-treatment) after therapeutic intervention (P < .05). The mean improvements were strongly statistically significant between S0 and S1 and between S1 andS2 (P < .0001) and less significant between S2 and S3 (P < .01). The mean improvement between 6 months (S3) and final follow-up (more than 12 months) was not statistically significant. The MRI findings demonstrated that the diffuse BMES in the femoral head and neck disappeared completely.HF-ESWT is a safe, effective, reliable, and noninvasive treatment in patients with painful BMES of the hip, and it can accelerate the recovery of BMES of the hip, shorten the treatment time and course of disease, improve hip joint function and the quality of life of patients.

How We Manage Bone Marrow Edema-An Interdisciplinary Approach

Bone marrow edema (BME) is a descriptive term for a common finding in magnetic resonance imaging (MRI). Although pain is the major symptom, BME differs in terms of its causal mechanisms, underlying disease, as well as treatment and prognosis. This complexity together with the lack of evidence-based guidelines, frequently makes the identification of underlying conditions and its management a major challenge. Unnecessary multiple consultations and delays in diagnosis as well as therapy indicate a need for interdisciplinary clinical recommendations. Therefore, an interdisciplinary task force was set up within our large osteology center consisting of specialists from internal medicine, endocrinology/diabetology, hematology/oncology, orthopedics, pediatrics, physical medicine, radiology, rheumatology, and trauma surgery to develop a consenus paper. After review of literature, review of practical experiences (expert opinion), and determination of consensus findings, an overview and an algorithm were developed with concise summaries of relevant aspects of the respective underlying disease including diagnostic measures, clinical features, differential diagnosis and treatment of BME. Together, our single-center consensus review on the management of BME may help improve the quality of care for these patients.

Transient Osteoporosis of the Hip: Risk and Therapy

Objective

The aim of this study was to investigate the impact of occupation in patients with transient osteoporosis of the hip (TOH). The study also compares two different types of management for this condition: conservative treatment and surgical drilling.

Methods

This was a retrospective case series study. The medical records for patients diagnosed with TOH at our institution within the period 2012–2017 were retrieved. General demographic data, clinical features, and diagnostic modalities were obtained. In addition, management procedures and their associated prognostic factors were acquired. The effectiveness of these procedures was assessed by the number of days of sick leave, the time needed for full recovery and the number of recurrences of TOH. Also, pain responses at 24 hrs, 48 hrs, and at 1 week were estimated subjectively through a “pain score” out of 10, and objectively through the degree of improvement in daily activity. The patients had a regular follow-up at 4- to 6-week intervals.

Results

In total, 15 cases of TOH, 14 men and one woman, were enrolled in the study. The mean age of the patients was 41 years (range 26–59 years). Out of the 15 cases, nine were healthcare professionals (eight physicians and one nurse). Ten patients underwent hip drilling for core decompression and five patients were treated conservatively. The time needed for full recovery was 5.8 weeks for those who underwent drilling, and 48.3 weeks for three patients receiving conservative treatment. The other two patients who were treated conservatively had not achieved full or near-full recovery at the time of reporting this study.

Conclusion

Physicians may be at increased risk of developing TOH. Further studies should be conducted to examine the role of this occupation as a risk factor. In addition, hip drilling should be considered as an effective treatment modality, especially in those patients who seek a faster recovery.

Repeated Low Back Pain Caused by Regional Migratory Osteoporosis of the Sacroiliac Joint

Introduction:

Regional migratory osteoporosis (RMO) is a rare, self-limiting disorder characterized by migratory arthralgia that mainly occurs in the weight-bearing joints of the lower extremities. RMO is most commonly observed in middle-aged men, and its etiology is unknown. We report the case of a middle-aged man who experienced repeated low back pain that was caused by RMO of the sacroiliac joint (SIJ).

Case Report:

In this case, the patient initially complained of left low back pain; however, there were no specific findings in plain radiography of the lumbar spine and pelvis. In addition, blood chemistry test findings were normal. Magnetic resonance imaging (MRI)revealed a diffuse bone marrow edema in the left SIJ. Conservative treatment was effective, and the pain was relieved within 3 months. However, 2 months later, a similar pain developed on the right side. MRI showed bone marrow edema in the right SIJ and the left-sided lesion had disappeared. The symptom was relieved by conservative treatment. After 5 months, the pain disappeared and the MRI findings became normal. During the next 2 years of follow-up, there is no recurrence of the illness.

Conclusions:

To the best of our knowledge, this is the first report of RMO with a lesion that moved to the SIJ of both sides. We believe that knowledge of this disorder can prevent invasive procedures, particularly, in treating a patient with low back pain.

Painful transient edema in the tibial diaphysis: the challenges and the essence of biopsy in treatment

BACKGROUND

Some patients experience a non-traumatic pain in the tibial diaphysis similar to that in the clinical and radiological findings of a tumor, an infection or a stress fracture and cannot be definitively diagnosed even after biopsy. In this study, our aim was to exhibit the challenges in the diagnosis of this patient group and to evaluate this type of patients with a limited population in the literature.

METHODS

Eighteen extremities of 16 patients, whose complaints of non-traumatic pain in the tibial diaphysis were evaluated by our tumor council and T2-weighted MR scans of the medullary bone had shown hyperintense signal changes or tumor-like appearances, were evaluated with histological, radiological, and clinical results.

RESULTS

Lesions were detected in 18 extremities of the 16 patients (seven males, nine females; mean age 23 [range 7 to 51] years). Four of the lesions were in the right tibial diaphysis, ten were in the left, and two were bilateral. Laboratory findings of the patients were normal. Based on the decision of the tumor council, biopsy was performed on 12 patients. All patients' complaints were gone and MRI findings decreased during the follow-up period. The complaints of the three patients who did not have a biopsy decreased after a mean period of three months.

CONCLUSIONS

Medullary stress syndrome has been reported in the literature in various forms and in a limited number of cases, including longitudinal stress fracture and transient medullary edema of the bone. In light of our findings, we deduced that biopsy of the diaphyseal lesions in this patient group is essential and that the complaints of this patient group declined in the earlier term in comparison to the patients who were not performed biopsy.

Transient Osteoporosis of the Hip: A Mysterious Cause of Hip Pain in Adults

BACKGROUND

Transient osteoporosis of the hip (TOH) is a poorly understood and forgotten clinical entity. The diagnosis is often delayed, and inappropriate treatment is provided, due to the lack of its awareness among the clinicians.

MATERIALS AND METHODS

Twelve patients (11 male and one female) within the age group of 35-50 years, were identified retrospectively from the hospital records between July 2011 and June 2015 who had evidence of TOH on clinical and radiological parameters.

RESULTS

All the patients were treated conservatively by nonweight bearing mobilization, anti-inflammatory drugs, bisphosphonates, calcium, and Vitamin D supplements. None of our patients had any symptoms after 6 months of conservative management. The disease did not progress, and there was no evidence of hip joint involvement in any of the cases. Plain radiographs were not diagnostic in the early detection of TOH. Magnetic resonance imaging was found to be highly specific and sensitive in diagnosing TOH. The clinical condition of TOH is characterized by its acute onset of hip pain in middle-aged people, and its symptoms are out of proportion to the radiological findings.

CONCLUSION

The TOH is a nondestructive and self-limiting condition of the hip, which responds well to the conservative treatment. We believe that TOH could be a subset of complex regional pain syndrome type 1, as it has many similarities in clinical presentation and management. Awareness of this entity is important to the clinicians for an early diagnosis and to avoid unnecessary treatment for other mimicking conditions.

Intractable bone marrow edema syndrome of the hip

There is a need for an effective and noninvasive treatment for intractable bone marrow edema syndrome of the hip. Forty-six patients with intractable bone marrow edema syndrome of the hip were retrospectively studied to compare the short-term clinical effects of treatment with high-energy extracorporeal shock wave therapy vs femoral head core decompression. The postoperative visual analog scale score decreased significantly more in the extracorporeal shock wave therapy group compared with the femoral head core decompression group (P<.05). For unilateral lesions, postoperative Harris Hip Scores for all hips in the extracorporeal shock wave therapy group were more significantly improved than Harris Hip Scores for all hips in the femoral head core decompression group (P<.05). Patients who underwent extracorporeal shock wave therapy also resumed daily activities significantly earlier. Average overall operative time was similar in both groups. Symptoms disappeared significantly sooner in the extracorporeal shock wave therapy group in patients with both unilateral (P<.01) and bilateral lesions (P<.05). Hospital costs were significantly lower with extracorporeal shock wave therapy compared with femoral head core decompression. The intraoperative fluoroscopy radiation dose was lower in extracorporeal shock wave therapy than in femoral head core decompression for both unilateral (P<.05) and bilateral lesions (P<.01). On magnetic resonance imaging (MRI), bone marrow edema improved in all patients during the follow-up period. After extracorporeal shock wave therapy, all patients remained pain-free and had normal findings on posttreatment radiographs and MRI scans. Extracorporeal shock wave therapy appears to be a valid, reliable, and noninvasive tool for rapidly resolving intractable bone marrow edema syndrome of the hip, and it has a low complication rate and relatively low cost compared with other conservative and surgical treatment approaches.

SPECT/CT versus MRI in patients with nonspecific pain of the hand and wrist - a pilot study

BACKGROUND

Hand and wrist pain is a diagnostic challenge for hand surgeons and radiologists due to the complex anatomy of the involved small structures. The American College of Radiology recommends MRI as the study of choice in patients with chronic wrist pain if radiographs are negative. Lately, state-of-the-art SPECT/CT systems have been introduced and may help in the diagnosis of this selected indication.

MATERIALS AND METHODS

This retrospective study included 21 patients with nonspecific pain of the hand/wrist. The diagnosis of nonspecific wrist pain was made by the referring hand surgeon based on patient history, clinical examination, plain radiography and clinical guidelines. All patients received planar early-phase imaging and late-phase SPECT/CT imaging as well as MRI. Lesions were divided into major (causative) and minor (not causative) pathologies according to clinical follow-up. Furthermore, oedema-like bone marrow changes seen on MRI were compared with focally increased tracer uptake seen on SPECT/CT images.

RESULTS

MRI yielded a quite high sensitivity (0.86), but a low specificity (0.20). In contrast, SPECT/CT yielded a high specificity (1.00) and a low sensitivity (0.71). Oedema-like bone marrow changes were detected in 15 lesions in 11 patients. In ten lesions with bone marrow oedema on MRI, foci of elevated tracer uptake were detected on SPECT/CT. Overall, MRI was more sensitive, but SPECT/CT was more specific in the evaluation of causative pathologies.

CONCLUSION

In this initial comparison, SPECT/CT showed higher specificity than MRI in the evaluation of causative pathologies in patients with nonspecific wrist pain. However, MRI was more sensitive. Thus, SPECT/CT was shown to be a useful problem-solving tool in the diagnostic work-up of these patients.

An unusual cause of hip pain

The authors describe a case of bilateral transient regional osteoporosis of the hips occurring in a primigravida patient, which resolved spontaneously postpartum, leaving no residual damage. The authors review the existing literature regarding this disease.

Transient osteoporosis of the hip/bone marrow edema syndrome with soft tissue involvement: a case report

Transient osteoporosis of the hip (TOH) is a rare condition mainly affecting pregnant women in their third trimester and middle aged men. We report a case of TOH/Bone marrow edema syndrome in pregnancy with involvement of the surrounding soft tissues on magnetic resonance image, which has not been previously reported. The presence of such edema in the soft tissues may help to differentiate this condition from early avascular necrosis of the hip, and may also provide an insight into the pathogenesis of the condition. The reported patient was treated conservatively and fully recovered.

[Transient bone marrow edema of the hip]

Transient bone marrow edema of the hip is characterized by moderate homogeneous low MR signal intensity with ill-defined margins that involves at least a portion of the femoral head. Spin echo T1-weighted images are helpful to exclude other underlying diseases (tumor, infection, necrosis from systemic origin…), for which marrow edema is secondary or no epiphyseal in location. High-resolution fat-suppressed T2-weighted or proton density images allow evaluation of the articular cartilage, subchondral bone and subchondal marrow: if the articular cartilage is abnormal, the lesion is irreversible (arthrosis or necrosis); if the subchondral bone is focally interrupted and/or if the femoral is no longer spherical, the lesion is irreversible (necrosis); if a focal linear fluid collection is present under the subchondral bone, the lesion is irreversible (necrosis). Finally, subchondral changes may provide useful prognostic information: the absence of any abnormality other than marrow edema typically indicates that complete resolution is likely; the presence of a focal T2-weighted hypointense lesion immediately next to the subchondral bone suggests an irreversible lesion, especially if it is equal to or thicker than 4mm or the joint space. In some instances, prognosis cannot be reliably determined requiring the need for follow-up imaging.

Relationship of idiopathic osteonecrosis of the femoral head to perfusion changes in the proximal femur by dynamic contrast-enhanced MRI

OBJECTIVE

The purpose of this article is to relate intramedullary perfusion of the proximal femur to severity of osteonecrosis of the femoral head by using dynamic contrast-enhanced MRI (DCE-MRI).

SUBJECTS AND METHODS

Twelve patients (14 symptomatic hips) who underwent DCE-MRI and had subsequent core decompression of the femoral head were examined. Hips were graded for severity according to MRI findings and were assigned scores of 0 (negative findings), 1 (focal marrow abnormalities), and 2 (subchondral collapse). Thirteen asymptomatic hips acted as controls. The DCE-MRI data were analyzed by use of a pharmacokinetic two-compartment model.

RESULTS

Compared with control hips, there was significantly greater peak enhancement in the femoral head in hips of all grades (p < 0.001) and in the femoral neck (p = 0.001) and intertrochanteric area (p = 0.001) in grade 2 hips. The time to peak was significantly delayed in the femoral head in grade 0 hips (p = 0.02) and in the intertrochanteric area in grade 2 hips (p = 0.003) compared with the controls.

CONCLUSION

As evaluated by DCE-MRI, intramedullary peak enhancement in the femoral head increased with progression of idiopathic osteonecrosis of the femoral head, whereas there was delayed peak enhancement in the femoral head in hips with negative findings and intertrochanteric stasis in advanced osteonecrosis of the femoral head. Such perfusion changes as shown on MRI can occur with early osteonecrosis in the absence of other MRI abnormalities.

Fracture complicating the bone marrow edema syndrome

Bone marrow edema syndrome (BMES), also known as transient regional osteoporosis, is a rare and poorly understood disease process. We present a case of an elderly patient with the BMES who had a relapsing and remitting course complicated by a hip fracture which presented the unique and a previously unreported opportunity to examine the bony architecture pathologically. The patient responded well to calcitonin and bisphosphonate therapy after surgical repair of his fracture.This case highlights an underappreciated potential complication of BMES. Though not previously reported in the literature, BMES may be associated with active osteoporotic changes, with an infrequent risk of fracture that may be amenable to potential therapeutic interventions. Pathologically, BMES may represent a spectrum of disease consisting of an osteoclast-rich phase (transient regional osteoporosis phase) predisposing to fracture in addition to the more indolent osteoclast-poor phase with bone marrow edema more commonly associated with the disease. We hypothesize that it is the osteoclastic-rich phase which may benefit from early introduction of weight bearing activities, calcitonin, bisphosphonates, or parathyroid hormone. For example, bisphosphonates reduce bone resorption directly. Indirectly, bisphosphonates may also increase osteoblast differentiation and number and thus improve bone quality, an added benefit in the treatment of bone involved in the BMES, whether in the osteoclast-rich or osteoclast-poor phase.Further study should evaluate this osteoclastic-rich phase, which may be a transient pathologic phenomenon and which has not been described previously. Transient regional osteoporosis, therefore, may represent one point in the spectrum of the BMES. Hence, we would argue that BMES is a more accurate name for the full spectrum of this disease entity.

Migrating transient osteoporosis of the hip in a 30-year-old man

Transient osteoporosis of hip is a condition of unknown etiology, presenting as painful limping, and characterized by osteopenia of the involved joint without preexisting disease or immobilization. Most of the cases were reported in middle-aged men, and one-third of the cases develop in women in the third trimester of pregnancy. The hypothesis that this condition leads to avascular necrosis of the hip has been disproved by various reports and hence does not warrant any surgical interference. This is a self limiting condition, which needs regular follow-up. The authors report a case of migrating transient osteoporosis of the hip in a 30-year-old man successfully treated with antiresorptive treatment.

Male transient hip osteoporosis: are physicians at a higher risk?

SUMMARY: Data of 17 male patients with a final diagnosis of transient osteoporosis (TO) of the hip seen at the radiology department of a university hospital over a period of 7 years were retrospectively studied. Comparison of the proportion of doctors among TO cases with that among other hip joint pathologies revealed a significant difference. PURPOSE: The objective of this study is to present clinical and radiological findings of hip TO and to assess the association of the condition with patients' occupation. MATERIALS AND METHODS: Data of 17 male patients with a final diagnosis of transient osteoporosis of the hip seen at the radiology department of a university hospital over a period of 7 years were retrospectively studied. RESULTS: The diagnosis of transient hip osteoporosis was in accordance with the published literature for clinical, imaging findings, and laboratory results. Among the 17 cases of male transient hip osteoporosis, 65% were physicians and 12% were commercial pilots. Comparison of the proportion of doctors among TO cases with that among other hip joint pathologies revealed a significant difference. Abnormal low hormone levels of testosterone and 25-cholicalciferol (vitamin D) were detected in three and two patients, respectively. CONCLUSION: The preponderance of physicians among patients with transient hip osteoporosis has not been previously reported. Etiological contribution of endocrine pathology and type of occupation to the causation of transient osteoporosis merits further research.

Bone marrow edema of the femoral head and transient osteoporosis of the hip

The current article of this issue aims at defining the generic term of bone marrow edema of the femoral head as seen at MR imaging. It must be kept in mind that this syndrome should be regarded, not as a specific diagnosis, but rather as a sign of an ongoing abnormal process that involves the femoral head and/or the hip joint. We aim at emphasizing the role of the radiologists in making a specific diagnosis, starting from a non-specific finding on T1-weighted images and by focusing on ancillary findings on T2-weighted SE or fat-saturated proton-density weighted MR images.

Histopathological perspective on bone marrow oedema, reactive bone change and haemorrhage

This article presents a systematic review of the current biomedical literature surrounding the aetiopathogenesis and histopathological features of bone marrow oedema, reactive bone change and haemorrhage. Bone marrow oedema is generally demonstrated as a non-specific finding on magnetic resonance imaging in association with infections, tumours and avascular necrosis. When it occurs in isolation as a primary event not triggered by any obvious bony pathology in the clinical setting of debilitating joint pain, it constitutes the "bone marrow oedema syndrome". Although the latter diagnosis is based on magnetic resonance (MR) imaging, showing the lesion as areas of signal hyperintensity within the marrow, recent radiology-histology correlational studies have shown variably interstitial marrow oedema, necrosis, fibrosis and trabecular bone abnormalities. In light of these facts, the use of the term bone marrow oedema syndrome in a radiological context might be considered questionable, but histopathological techniques are not sensitive in detecting increased extracellular fluid. Reactive bone changes may be focal or diffuse and usually amount to increased bone formation. Bone marrow haemorrhage, due to trauma, results in bone bruising, a condition in which the size of the bruise and associated osteochondral injury determines the outcome, although the natural history of these lesions is still being researched.

Subchondral fracture of the femoral head in healthy adults

Subchondral fracture of the femoral head has been reported to occur as an insufficiency fracture associated with poor bone quality or as a fatigue fracture in young military recruits. Transient osteoporosis of the hip has clinical and imaging findings that resemble those of a subchondral fracture, but it usually occurs in healthy middle-aged people not involved in sports or similar activities. The clinical aspects of five cases of subchondral fracture of the femoral head occurring in four healthy adults without antecedent trauma were evaluated. Of particular interest were whether subchondral fracture of the femoral head could occur without a sudden increase in daily activity and what differences could be detected from the imaging and clinical courses between subchondral fracture of the femoral head and transient osteoporosis of the hip. Three cases of subchondral fracture of the femoral head occurred without an increase in daily activity. The only difference in imaging findings between subchondral fracture of the femoral head and transient osteoporosis of the hip was the existence of a subchondral fracture line seen on magnetic resonance images of a subchondral fracture of the femoral head. The clinical courses of these disorders were similar. These findings suggest transient osteoporosis of the hip and subchondral fracture of the femoral head are subchondral bone injuries of different severity.

LEVEL OF EVIDENCE

Level IV, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

MR Imaging of the Hip: Osseous Lesions

Because of the exquisite soft tissue contrast resolution of MR imaging combined with recent technologic developments, a variety of conditions involving the hip joint and adjacent bony structures can be well evaluated using MR imaging, with or without contrast material. Among the different conditions, hip trauma and avascular necrosis are the most frequent indications. Other entities for which MR imaging has proven its usefulness include subchondral fractures, osteochondritis dissecans, transient osteoporosis, bone tumors, inflammatory and infectious processes, and a variety of bone marrow disorders.

Fatty marrow conversion of the proximal femoral metaphysis in transient bone marrow edema syndrome

INTRODUCTION

In the proximal femoral metaphysis, hematopoietic marrow is predominant during the adult stage of life. The conversion of hematopoietic marrow to fatty marrow in the proximal femoral metaphysis has been suggested as an etiologic factor of ischemia in the pathogenesis of femoral head osteonecrosis. To determine whether the chronology of fatty marrow conversion of the proximal femoral metaphysis is related to transient bone marrow edema syndrome of the hip, a case control study was conducted on 10 patients with the disease.

MATERIALS AND METHODS

There were 8 men and 2 women with a mean age of 33 years (range 19-45 years). The 10 patients were matched with 20 controls for gender and age (5-year range). T1-weighted MRI scans of their hips were reviewed. Marrow of the greater trochanter becomes fatty before puberty, and thus, the greater trochanter can be used as a built-in control. The signal intensity of the proximal femoral metaphysis was compared to that of the greater trochanter.

RESULTS

In all patients, the signal intensity of the proximal femoral metaphysis was isointense (fatty marrow) relative to that of the greater trochanter. In control subjects, the signal intensity was isointense in 8 (40%) and hypointense (hematopoietic marrow) in 12 (60%) (p < 0.05).

CONCLUSION

The current study shows that the proximal femoral metaphysis is predominantly fatty in transient bone marrow edema syndrome. The conversion of hematopoietic to fatty marrow is known to correlate with decreases in intramedullary blood flow. Thus, the current study suggests that an ischemia of the proximal femur secondary to fatty marrow conversion of the proximal femoral metaphysis might be a cause of transient bone marrow edema syndrome of the hip.

MR imaging findings in transient osteoporosis of the hip

PURPOSE

The authors sought to describe the magnetic resonance (MR) imaging findings including perfusion imaging, in association with the course of acute bone marrow oedema syndrome (aBMEs), in a group of patients with acute hip pain and a final diagnosis of transient osteoporosis of the hip (TOH).

MATERIALS AND METHODS

From 217 patients referred with a probable diagnosis of avascular necrosis (AVN) of the femoral head, we identified 42 patients who had clinical and radiographic findings not relevant to AVN. MR imaging examinations were performed on a 1.0T scanner. Perfusion imaging was performed in 20 patients. The bone marrow oedema (BME) was classified in four stages. In addition, the presence or absence of oedema in the subchondral area and the presence of other subchondral lesions were recorded. Acetabular bone marrow was also assessed for the presence of oedema. The quantitative measurements included: maximum size of the effusion, percentage of enhancement (PE) and time of peak enhancement of abnormal marrow compared to the first pass, on the perfusion images.

RESULTS

Osteopenia was present on plain radiographs in 87% of cases. The most common pattern of BME was extending to the femoral head and neck. Acetabulum was involved in 16.6%. In 22.6% the BME spared the subchondral region of the femoral head. There were two cases (4.7%) with subchondral changes. A joint effusion was noted in 33 of the 42 patients. On perfusion imaging, a delayed peak enhancement was noted in 20 patients between 40 and 65 s after the first pass of contrast. No patient had any evidence of femoral head collapse or change in sphericity on follow-up MRI. None of the patients developed avascular necrosis in a time frame of 18 months from the onset of the acute hip pain.

CONCLUSION

The aBMEs MR imaging pattern varies and is most commonly appearing on X-rays as osteopenia. Absence of subcondral lesions, delayed peak enhancement of the abnormal marrow on perfusion images, and sparing of subchondral zone from marrow oedema are MR imaging findings highly correlated to TOH.